faulty TRV question

[paperboy1984]

Hey guys

I was told my TRV on my bedroom rad was faulty-as no heat was going to it, the pipes even felt cold. I don't understand how the pipes being cold makes the TRV faulty - surely they would be hot still!!

ANyway I am going to change my TRV-but the one I have is a drayton and it's quite old. If i buy a similar one will it fit-are they standard sizes? i know they are all 1/2" fittings...

 

[gas4you]

If the valve is jammed shut then no flow is going through the radiator so no hot water will be flowing through the pipes to it.

Before replacing it try tapping the pin under the head firmly but with care to see if it can be released.

A new Drayton will fit the old 1/2" threads ok.

 

[paperboy1984]

yep but surely hot water would still be flowing up to the rad (the pipes that come up through the floor and before the valve!!

yep i have just tapped the pin and it is jammed in badly. so i will have to change the valve. should i also change the tail? i know a radiator/allen key is designed for this, and some tails can be tightened/loosened with an adjustable, depending on design.

my other query is - i have a 3 port valve (mid-position-honeywell V4073A). If i drain the system - should I put it in the manual position. what difference will this make though? thanks.

 

[Registered Gas Man]

yep but surely hot water would still be flowing up to the rad (the pipes that come up through the floor and before the valve!!

Nope they shouldn't. The knackered valve has stopped the flow through that rad/part of the heating system. The pump can not send hot water through a dead end.

so i will have to change the valve. should i also change the tail?

No.

i have a 3 port valve (mid-position-Honeywell V4073A). If i drain the system - should I put it in the manual position. what difference will this make though?

Yes. It will be open so will allow water to flow. I guess its a similar situation to your first question.

 

[paperboy1984]

thank you for this help. it's a good point about the 3 port valve. i suppose if on the other hand you were changing the hot water cylinder you would have to drain the circuit on both manual and automatic!!! ??

 

[Registered Gas Man]

Nope. When in manual the valve is in mid position allowing both circuits to drain.